System and method for estimating the crystallinity of stacked metal lines in microstructures

ABSTRACT

By performing x-ray analysis of stacked metallization layers on the basis of data reduction, the crystalline structure of individual metallization layers may be determined. Consequently, a relationship between electromigration and crystallinity, as well as a correlation between process parameters and materials and the finally obtained crystalline structures of metal lines, may be estimated in a highly efficient manner compared to measurement techniques based on charged particles.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Generally, the present invention relates to the formation ofmicrostructures, such as advanced integrated circuits, and, moreparticularly, to the formation and non-destructive examination ofconductive structures, such as metal regions, and their characteristicsduring stress conditions.

2. Description of the Related Art

In the fabrication of modern microstructures, such as integratedcircuits, there is a continuous drive to steadily reduce the featuresizes of microstructure elements, thereby enhancing the functionality ofthese structures. For instance, in modern integrated circuits, minimumfeature sizes, such as the channel length of field effect transistors,have reached the deep sub-micron range, thereby increasing performanceof these circuits in terms of speed and/or power consumption. As thesize of individual circuit elements is reduced with every new circuitgeneration, thereby improving, for example, the switching speed of thetransistor elements, the available floor space for interconnect lineselectrically connecting the individual circuit elements is alsodecreased. Consequently, the dimensions of these inter-connect lineshave to be reduced to compensate for a reduced amount of available floorspace and for an increased number of circuit elements provided per unitdie area. The reduced cross-sectional area of the interconnect lines,possibly in combination with an increase of the static power consumptionof extremely scaled transistor elements, may require a plurality ofstacked metallization layers in order to meet the requirements in viewof a tolerable current density in the metal lines.

Advanced integrated circuits, including transistor elements having acritical dimension of 0.13 μm and even less, may, however, requiresignificantly increased current densities in the individual interconnectlines, despite the provision of a relatively large number ofmetallization layers, owing to the significant number of circuitelements per unit area. Operating the interconnect lines at elevatedcurrent densities, however, may entail a plurality of problems relatedto stress-induced line degradation, which may finally lead to apremature failure of the integrated circuit. One prominent phenomenon inthis respect is the current-induced material transportation in metallines, also referred to as “electromigration,” which may lead to theformation of voids within and hillocks next to the metal line, therebyresulting in reduced performance and reliability or complete failure ofthe device. For instance, aluminum lines embedded into silicon dioxideand/or silicon nitride are frequently used as metal for metallizationlayers, wherein, as explained above, advanced integrated circuits havingcritical dimensions of 0.13 μm or less, may require significantlyreduced cross-sectional areas of the metal lines and, thus, increasedcurrent densities, which may render aluminum less attractive for theformation of metallization layers.

Consequently, aluminum is increasingly being replaced by copper andalloys thereof that exhibit a significantly lower specific resistivityand exhibit significant electromigration effects at considerably highercurrent densities compared to aluminum. The introduction of copper intothe fabrication of microstructures and integrated circuits comes alongwith a plurality of severe problems residing in copper's characteristicto readily diffuse in silicon dioxide and a plurality of low-kdielectric materials and to have a moderately low adhesion to the low-kdielectrics. To provide the necessary adhesion and to avoid theundesired diffusion of copper atoms into sensitive device regions, itis, therefore, usually necessary to provide a barrier layer between thecopper and the dielectric material in which the copper lines areembedded. Although silicon nitride is a dielectric material thateffectively prevents the diffusion of copper atoms, selecting siliconnitride as an interlayer dielectric material is less than desirable,since silicon nitride exhibits a moderately high permittivity, therebyincreasing the parasitic capacitances of neighboring copper lines.Hence, a thin conductive barrier layer that also imparts the requiredmechanical stability to the copper is formed to separate the bulk copperfrom the surrounding dielectric material and only a thin silicon nitrideor silicon carbide or silicon carbonitride layer in the form of acapping layer is frequently used in copper-based metallization layers.Currently, tantalum, titanium, tungsten and their compounds withnitrogen and silicon and the like are preferred candidates for aconductive barrier layer, wherein the barrier layer may comprise two ormore sub-layers of different composition so as to meet the requirementsin terms of diffusion suppressing and adhesion properties.

Another characteristic of copper significantly distinguishing it fromaluminum is the fact that copper may not be readily deposited in largeramounts by chemical and physical vapor deposition techniques, inaddition to the fact that copper may not be efficiently patterned byanisotropic dry etch processes, thereby requiring a process strategythat is commonly referred to as the damascene or inlaid technique. Inthe damascene process, a dielectric layer is first formed which is thenpatterned to include trenches and vias which are subsequently filledwith copper, wherein, as previously noted, prior to filling in thecopper, a conductive barrier layer may typically be formed on sidewallsof the trenches and vias. The deposition of the bulk copper materialinto the trenches and vias is usually accomplished by wet chemicaldeposition processes, such as electroplating and electroless plating,thereby requiring the reliable filling of vias with an aspect ratio of 5and more with a diameter of 0.3 μm or even less in combination withtrenches having a width ranging from 0.1 μm to several μm. Althoughelectrochemical deposition processes for copper are well established inthe field of electronic circuit board fabrication, a substantiallyvoid-free filling of high aspect ratio vias is an extremely complex andchallenging task, wherein the characteristics of the finally obtainedcopper metal line significantly depend on process parameters, materialsand geometry of the structure of interest. Since the geometry ofinterconnect structures is determined by the design requirements and maynot, therefore, be significantly altered for a given microstructure, itis of great importance to estimate and control the impact of materials,such as conductive and non-conductive barrier layers, of the coppermicrostructure and their mutual interaction on the characteristics ofthe interconnect structure so as to insure both high yield and therequired product reliability. In particular, it is important to identifyand monitor degradation and failure mechanisms in interconnectstructures for various configurations so as to maintain devicereliability for every new device generation or technology node.

One important aspect of copper-based lines and regions with respect toperformance is the crystalline structure of the copper and copperalloys, since the effective resistance of the copper lines may dependsignificantly on the number, size and orientation of the crystal grainsin the metal lines. Consequently, the materials used and also theprocesses used, such as deposition and post-deposition processes, mayhave a significant influence on the performance of these lines.Furthermore, any operational conditions may alter the crystallinestructure, thereby also contributing to a performance degradation. Otherdegradation processes, such as stress-induced material transport, forexample electromigration, may affect the crystallinity of the metal.Thus, great efforts are made in investigating the effect of metal grainson the overall performance of metallization structures, wherein,however, usually complex and destructive measurement procedures may berequired. Consequently, a “direct” observation of process- andmaterial-caused effects as well as operation-driven influences on thecrystallinity of metal lines may be time-consuming, in particular, whenthe performance of a plurality of stacked metallization layers has to beevaluated in its entirety.

Since advanced microstructures, such as fast microprocessors, mayrequire increasingly complex interconnects with dense metal structuresat extremely reduced dimensions and many inspection techniques arealready pushed to their limits, there exists a need for enhanced oralternative techniques, while avoiding or at least reducing one or moreof the above-identified problems.

SUMMARY OF THE INVENTION

The following presents a simplified summary of the invention in order toprovide a basic understanding of some aspects of the invention. Thissummary is not an exhaustive overview of the invention. It is notintended to identify key or critical elements of the invention or todelineate the scope of the invention. Its sole purpose is to presentsome concepts in a simplified form as a prelude to the more detaileddescription that is discussed later.

Generally, the present invention relates to a technique for monitoringand/or examining and/or controlling the process of manufacturing highlycomplex metallization structures, such as copper-based metallizationlayer stacks of sophisticated integrated circuits, with respect totexture-related characteristics, such as size and/or orientation ofmetal grains in respective metal regions on the basis of x-ray analysis,wherein one or more metallization layers may be subjected to measurementin the presence of still other metallization layers of the metal stack.Consequently, physical failure analysis and reliability studies ofhighly complex metallization structures, which are usually performed onthe basis of charged particle microscopy, may be performed on the basisof x-ray analysis, thereby substantially avoiding negative impact on thecharacteristics of the metallization stack caused by the measurementprocess itself. For example, in highly complex copper-basedmetallization layer stacks including low-k dielectric materials,conventional metrology processes based on charged particle microscopy,such as SEM (scanning electron microscopy), may result in a significantdeformation, thereby possibly yielding non-reliable measurement resultsand also imposing significant constraints with respect to themeasurement strategy, due to the substantial “non-transparency” of upperlayers with respect to intermediate metallization layers.

Consequently, according to the present invention, the characteristics ofx-rays, i.e., their ability to penetrate a significant length into themetallization stack, is exploited in order to obtain substantiallythree-dimensional information that may include data with respect tograin size and/or grain orientation of the various metallization layers.Based on this three-dimensional measurement data, a “data reduction” maybe performed in order to obtain desired texture information in asubstantially two-dimensional fashion in order to enable the estimationof texture-specific characteristics of one or more metallization layersof the metal stack. Consequently, the high penetration capability of thex-rays may be taken advantage of so as to extract crystallographicinformation, while on the other hand, by appropriate data reduction,non-desired information may be suppressed, thereby providing thepotential for obtaining crystallographic information in a“layer-resolved” manner. Moreover, due to the advantages of x-rayanalysis with respect to sample preparation, that is, the correspondingmetallization layer stack may remain fully operational, examination ofstress-induced degradation mechanisms may be readily performed, whereinrespective measurement data may be obtained with none or only minordelays, thereby also providing the possibility of studying degradationeffects in a highly time-resolved manner and/or using the measurementdata as an efficient process control in adjusting the crystallinestructure of the metallization layers during the correspondingmanufacturing process.

According to one illustrative embodiment of the present invention, amethod comprises irradiating a portion of a first stacked metallizationstructure of a microstructure device with an x-ray beam of specifiedcharacteristics, wherein the first stacked metallization structurecomprises a plurality of layers and each layer comprises a metal region.The method further comprises obtaining first measurement data of theportion on the basis of the x-ray beam and manipulating the firstmeasurement data to obtain manipulated data relating to a texture of oneor more of the metal regions. Furthermore, the method comprisesextracting information for at least one of the plurality of stackedlayers about the texture on the basis of the manipulated data.

According to another illustrative embodiment of the present invention, amethod comprises forming a stacked metallization structure of amicrostructure device according to a specified manufacturing sequence,wherein the stacked metallization structure comprises a plurality ofmetallization layers. The method further comprises obtaining informationabout a texture of metal regions located in two or more of the pluralityof metallization layers on the basis of x-ray analysis and correlatingat least one process parameter used in the specified manufacturingsequence with the texture information. Finally, the at least one processparameter is controlled on the basis of the correlation.

According to yet another illustrative embodiment of the presentinvention, a method comprises providing a metallization structure of amicrostructure device, wherein the metallization structure comprises aplurality of stacked metallization layers, each of which comprises ametal region with metal grains. Furthermore, the metallization structureis subjected to predefined stress conditions and a distribution of grainorientations is estimated in at least one of the plurality of stackedmetallization layers by x-ray analysis under the predefined stressconditions.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be understood by reference to the followingdescription taken in conjunction with the accompanying drawings, inwhich like reference numerals identify like elements, and in which:

FIG. 1 a schematically illustrates a cross-sectional view of ametallization structure, such as a stack of copper-based metallizationlayers of an integrated circuit that may be subjected to atexture-related x-ray analysis according to the present invention;

FIG. 1 b schematically illustrates a top view of a metallization layerincluding metal regions, the grain size and/or orientation of which maybe estimated on the basis of an analysis technique according toillustrative embodiments of the present invention;

FIG. 1 c illustrates a schematic cross-sectional view of a multi-layermetallization stack during the incidence of an x-ray beam for analysisof texture-related characteristics of one or more metallization layersaccording to illustrative embodiments of the present invention;

FIG. 1 d schematically illustrates a cross-sectional view of amicrostructure device including one metallization layer for obtainingmeasurement data relating to texture-related characteristics accordingto an illustrative embodiment;

FIG. 1 e schematically illustrates a cross-sectional view of themicrostructure device including two stacked metallization layers forobtaining a further measurement data that may be used in combinationwith the previously obtained measurement data according to illustrativeembodiments;

FIG. 1 f schematically illustrates a data manipulation process in asimplified form for obtaining manipulated data including information onthe texture characteristics of a single layer of the stack of FIG. 1 eaccording to one illustrative embodiment of the present invention;

FIG. 2 schematically illustrates a system for estimatingtexture-specific characteristics of a metallization stack underspecified stress conditions according to illustrative embodiments of thepresent invention; and

FIG. 3 schematically illustrates a specific manufacturing environmentfor forming a stacked metallization structure by controlling at leastone process parameter on the basis of texture-specific informationobtained from one or more metallization structures formed in themanufacturing environment.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and are herein described in detail. It shouldbe understood, however, that the description herein of specificembodiments is not intended to limit the invention to the particularforms disclosed, but on the contrary, the intention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

Illustrative embodiments of the invention are described below. In theinterest of clarity, not all features of an actual implementation aredescribed in this specification. It will of course be appreciated thatin the development of any such actual embodiment, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which will vary from one implementation toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming, but would nevertheless be a routineundertaking for those of ordinary skill in the art having the benefit ofthis disclosure.

The present invention will now be described with reference to theattached figures. Various structures, systems and devices areschematically depicted in the drawings for purposes of explanation onlyand so as to not obscure the present invention with details that arewell known to those skilled in the art. Nevertheless, the attacheddrawings are included to describe and explain illustrative examples ofthe present invention. The words and phrases used herein should beunderstood and interpreted to have a meaning consistent with theunderstanding of those words and phrases by those skilled in therelevant art. No special definition of a term or phrase, i. e., adefinition that is different from the ordinary and customary meaning asunderstood by those skilled in the art, is intended to be implied byconsistent usage of the term or phrase herein. To the extent that a termor phrase is intended to have a special meaning, i.e., a meaning otherthan that understood by skilled artisans, such a special definition willbe expressly set forth in the specification in a definitional mannerthat directly and unequivocally provides the special definition for theterm or phrase.

Generally, the present invention provides a technique for obtaininginformation with respect to texture-specific characteristics of ametallization layer, which is one of a plurality of metallization layersin a corresponding metallization structure. The information is obtainedon the basis of x-ray measurement data, which may be appropriatelymanipulated so as to enable the extraction of layer-specific informationwithout requiring a specific sample preparation for removing orotherwise manipulating the structure of lower-lying metallizationlayers. Consequently, a high degree of authenticity of the extractedinformation relating to texture-specific characteristics, such as thedistribution of grain orientations of metal regions and the like, may beaccomplished since the respective metallization structures may bemaintained fully operational, while at the same time significantlyreducing any negative impact of the measurement procedure itself on thecharacteristics of the metallization stack. As previously explained, inhighly advanced microstructure devices, such as microprocessors, complexASICs or other integrated circuits, highly conductive metals, such ascopper, copper alloys and the like, are processed, possibly incombination with respective conductive and dielectric barrier layers,typically in conjunction with low-k dielectric materials, whereinmaterials, process techniques and environmental conditions during theoperation of the finalized semiconductor devices may significantlyaffect the performance of the respective metallization structure. Forexample, stress-induced degradation mechanisms, such as electromigrationand the like, although intensively studied, may be highly complex andare typically not yet fully understood, thereby requiring meaningful andrelevant information with respect to the mutual influences of materials,processes and operational conditions on the reliability of themetallization structure under consideration. In particular, thecrystalline structure of the metal lines in sophisticated integratedcircuits, typically comprising copper as the main ingredient, may havean increasingly decisive influence as feature sizes of metal lines aresteadily reduced. Thus, the influence of materials, process techniquesand operational conditions with respect to the crystallinity of thecorresponding metal structures is of great importance for enhancingperformance and reliability of presently existing and futuresemiconductor devices. Since x-ray analysis provides a means for probingdeeply into metallization structures without significant negative impacton the metal lines and dielectric materials provided in the respectivemetallization layer, the texture-specific characteristics thereof may beexamined under a variety of conditions, wherein the “data reduction” ofthe present invention enables the extraction of information for aspecific metallization level even if a plurality of furthermetallization layers are present. Hence, valuable information withrespect to grain distribution, grain size and the like may be obtainedin a reliable yet fast and efficient manner.

It should be noted that the present invention is particularlyadvantageous in the context of copper-based interconnect structuressince these structures will preferably be used in advancedmicrostructures, such as fast and powerful microprocessors, whereinespecially the problem of electromigration may significantly impactfurther developments in fabricating sophisticated integrated circuits.The principles of the present invention may, however, be readily appliedto any microstructure of interest, in which stress-induced masstransport phenomena may significantly influence the operation and thereliability of the microstructure. Consequently, stress-inducedmigration problems and their influence on texture-relatedcharacteristics of materials may be effectively investigated for anytype of interesting conductive material, such as metals, metal alloys ormetal compounds used in present and future microstructure systems. Thepresent invention should therefore not be considered as being restrictedto copper-based interconnect structures unless such restrictions areexplicitly set forth in specific embodiments as presented in thefollowing description as well as in the appended claims.

As is well known, the degradation of inlaid, i.e., embedded, metal linesis related to directed mass transport within the line. The gradient ofthe electrical potential gives migrating atoms a preferred direction tothe anode. Local temperature peaks caused by increased electricalcurrent densities lead to temperature gradients during operation of amicrostructure device and therefore also thermal migration is closelyconnected with electromigration. Furthermore, mechanical stressgradients may also have a significant influence on the characteristicsof metal lines and thus on their crystallinity. Since the size andorientation of grains within the metal lines may significantly determinetheir characteristics with respect to performance and reliability, theprocess techniques for forming the metal lines as well as the materialsinvolved may have to be thoroughly monitored and controlled in order tomaintain device reliability and performance. Consequently, the presentinvention provides, in some aspects, the potential of a sensitiveprocess control or monitoring based on statistically relevantinformation and for the study of texture-specific alteration mechanismsfor highly authentic samples enhancing the understanding of many aspectsof the interconnect technology and reduced reliability related failuresin interconnect structures. To this end, fully embedded and operationalinterconnect structures, or any intermediate forms thereof, including aplurality of metallization levels may be subjected to specified stressconditions while monitoring texture-specific characteristics of theinterconnect structure in a spatially highly resolved fashion, that is,providing information of the distribution of grain orientations in a“layer resolved” manner. Since the analysis is based on x-raytechnology, low impact on the operational behavior of the sample as wellas rapid data gathering may be accomplished, thereby providing thepotential for effectively visualizing even subtle changes of the grainstructure of metal interconnect structures during operation. Moreover,these characteristics of the measurement technique of the presentinvention also provide the possibility of obtaining valuable informationon the “quality” of the respective manufacturing sequence forfabricating a specific type of metallization structure, which thereforemay enable an efficient process control, since information obtained onthe crystallinity of the respective metal level may even be provided inthe form of “inline” measurement data.

With reference to FIGS. 1 a-1 f, 2 and 3, further illustrativeembodiments of the present invention will now be described in moredetail. FIG. 1 a schematically illustrates a cross-sectional view of amicrostructure device 100, which in some illustrative embodiments mayrepresent a test structure used for the formation of sophisticatedintegrated circuits or may represent a portion of an actualsemiconductor device. The microstructure device 100 may comprise asubstrate 101, such as a semiconductor substrate or any otherappropriate carrier for forming therein and thereon respective circuitelements of an integrated circuit. In other cases, the substrate 101 mayact as a carrier for a stacked metallization structure 150 formedthereon. The stacked metallization structure 150 may comprise aplurality of individual metallization layers 110A, 110B, 110C, 110N,wherein the number N of metallization layers 110 may depend on deviceand process requirements. For example, the number of metallizationlayers 110A, 110B, 110C, 110N may range from 2-10 or more, wherein, forinstance, for highly complex copper-based microprocessors, approximately5-10 metallization layers 110A, 110B, 110C, 110N may typically beprovided.

Each of the metallization layers 110A, 110B, 110C, 110N may include oneor more metal regions 111 which may, in illustrative embodiments,comprise copper or copper alloys, or any other highly conductivematerials. For example, typically in copper-based metallizationstructures, the metal regions 111 may be confined by conductive and/ordielectric barrier layers, wherein conductive barrier layers maycomprise well-approved materials, such as tantalum, tantalum nitride,titanium, titanium nitride, tungsten, tungsten nitride,cobalt/tungsten/phosphorous compounds, cobalt/tungsten/boron compoundsand the like. For example, a conductive barrier layer 112 and adielectric capping layer 113, for instance comprised of silicon carbide,silicon nitride, nitrogen-enriched silicon carbide, or any combinationsthereof, may be provided for the metal regions 111 in the firstmetallization layer 110A. As a further example, a conductive cappinglayer 114 in combination with the conductive barrier layer 112 may beprovided for the metal regions 111 of the second metallization layer110B in order to demonstrate various design possibilities for thestacked metallization structure 150. Furthermore, the metal regions 111in the various metallization layers 110A, 110B, 110C, 110N may have anygeometric configuration as prescribed by design rules wherein, however,the essential portion of the metal material in the various regions 111may be provided in the form of metal lines and metal plates, while onlya minor portion of the metal material may be contained in respectivevias 115.

Furthermore, each of the metallization layers 110A, 110B, 110C, 110N maycomprise a dielectric layer 116, in which the metal regions 111 areembedded, wherein, depending on device requirements, the dielectriclayers 116 may have a differing configuration and may comprisewell-approved dielectric materials, such as silicon dioxide, siliconnitride, silicon oxynitride, silicon carbide and the like, possibly incombination with low-k dielectric materials, which may have a relativepermittivity of 3.0 and significantly less. It should be appreciatedthat although the microstructure device 100 may represent a specifictest structure fabricated on dedicated test wafers or on product wafersat specific locations, such as scribe lines and the like, theconfiguration of the metallization layer stack 150 may have a highdegree of similarity to a corresponding metallization structure ofactual product devices in order to provide high authenticity ofmeasurement data gathered on the basis of the structure 100 as shown inFIG. 1 a. That is, although the various metallization layers 110A, 110B,110C, 110N may be designed so as to enable, in some illustrativeembodiments, the operation of the structure 150 according to a specifiedtest regime, nevertheless the corresponding components of eachmetallization layer may be formed in accordance with design rules ofactual devices. In other illustrative embodiments, when the electricalfunctionality of the structure 150 may not be required for obtaining thedesired information, the design of the metallization structure 150 maybe identical to that of actual product devices.

A typical process flow for forming the microstructure device 100 asshown in FIG. 1 a may comprise the following processes, wherein, forconvenience, the fabrication of only one metallization layer, forinstance the layer 110A, will be described in more detail. Thus, afterforming any circuit elements or other microstructural features in and onthe substrate 101, when the substrate 101 is to represent a productsubstrate in which the device 100 is to be fabricated, the dielectriclayer 116 may be formed on the basis of any appropriate technique. Forinstance, the dielectric layer 116 may comprise a dielectric etch stoplayer (not shown) which may be used during the patterning of thedielectric material for forming any vias, such as the via 115 in thesecond metallization layer 110B, wherein well-established depositiontechniques such as plasma enhanced chemical vapor deposition (PECVD) andthe like may be used. Thereafter, the layer 116 may be formed in one ormore manufacturing steps, depending on the configuration of the layer116, wherein the fabrication of the metal regions 111 may be performedafter patterning of the dielectric layer 116 or prior to forming thelayer 116, when the metal regions 111 are first formed in a sacrificialmaterial, which may be removed after the formation of the metal regions111. In any case, any appropriate material may be used, such as polymermaterials, porous silicon-based dielectric materials and the like.

The conductive barrier layer 112, if provided, may be formed by anyappropriate manufacturing technique, such as physical vapor deposition(PVD), sputter deposition, chemical vapor deposition (CVD), atomic layerdeposition (ALD), electrochemical deposition and the like. Thereafter,the highly conductive metal may be deposited on the basis of anyappropriate technique, wherein, for copper-based metallizationstructures, typically electrochemical deposition techniques, such aselectroplating, electroless plating and the like, may be used.

During the formation of the metal regions, the corresponding processtechnique may have a significant influence on the finally obtainedcrystallinity of the metal within the regions 111 with respect to agrain size and/or grain orientation. For example, frequently a so-calledseed layer may be used prior to the deposition of the bulk material byelectroplating, wherein the characteristics of the seed layer maysignificantly affect the crystalline structure of the resulting metal.As an example, CVD-deposited copper may, despite its advantageousbehavior with respect to step coverage, result in a copper that isinferior with respect to its crystallinity compared to asputter-deposited seed layer. Moreover, the electrochemical depositionprocess itself as well as any post-deposition processes may also affectthe finally obtained crystallinity. For instance, after the depositionof the corresponding metal, such as copper, typically excess material isformed on the dielectric layer 116, which has to be removed afterwardson the basis of electrochemical etch techniques and/or chemicalmechanical polishing (CMP), which may apply a high mechanical stress tothe resulting metal regions especially for low-k dielectric materialswithin the layer 116, as these low-k dielectric layers typically exhibita significantly lower mechanical stability. Thus, after deposition andpossibly after CMP, appropriate anneal processes may be performed inorder to improve the crystalline structure of the resulting metalregions 111.

FIG. 1 b schematically illustrates a top view of the device 100, whereina plurality of metal regions 111, for instance in the form of metallines, may be provided. After the above-described process sequence, themetal lines 111 may have a specific texture, that is, the metal in thelines 111 may comprise a plurality of metal grains 117, which mayrepresent a more or less crystalline area. Typically, a width of themetal line 111 may be significantly less than 1 μm, at least inlower-lying metallization layers such as layers 111A, 111B insophisticated semiconductor devices, while a length of the metal line111 may extend along several tenths of micrometers. Frequently, in viewof electrical performance, it may be desirable to provide a reducednumber of grains 117 within a single metal line 111 in order to reducescattering events for the charge carriers at grain boundaries 117A.Consequently, during the manufacturing of the various metallizationlayers 110A . . . 110N, process techniques may be used in order toreduce the number of grain boundaries 117A, that is, to increase thesize of the individual grains 117 in each metal line 111. Moreover, theperformance of the metal line 111 may also depend on the crystallineorientation of the respective grains 117, since differentcrystallographic orientation with respect to the length direction orperpendicularly thereto may also significantly influence thecharacteristics with respect to charge carrier transport and/orstress-induced degradation effects, such as electromigration. Forinstance, for copper-based metallization layers, the lines 111 havingcopper grains 117 with a crystallographic orientation (111)perpendicular to the drawing plane of FIG. 1 b may exhibit a higherresistance to electromigration than other orientations of coppercrystals. Consequently, it is important to monitor the characteristicsof the metal grains 117 during the complex process of manufacturing thesame and/or during the operation of the device 100, wherein an influenceof the measuring strategy on the obtained information should bemaintained at a low level in order to provide a high degree ofauthenticity, thereby rendering conventional techniques based on chargedparticles less efficient, due to the low penetration depth requiringsophisticated sample preparation techniques which, in combination withthe physical interaction of the charged particles, may significantlyaffect the overall configuration of the sample.

FIG. 1 c schematically illustrates the microstructure device 100, inwhich the metallization structure 150 may comprise, for example, sixmetallization layers, also indicated as M1, M2, M3, M4, M5, M6 which maycorrespond to the layers 110A . . . 110N as illustrated and explainedwith reference to FIGS. 1 a and 1 b. For example, the metallizationstructure 150 may be formed in accordance with design rulescorresponding to those of respective metallization layers ofcopper-based integrated circuits and the like. Consequently, in someillustrative embodiments, the metallization layers M1, M2 M3, M4, M5, M6may have experienced the same manufacturing sequences, metrologyprocesses and the like as any devices on product substrates, or themicrostructure device 100 may also be provided on a product substrate atdedicated test positions, while in other embodiments the structure 100may represent an actual product device used for test purposes. For aprobing beam, the metallization structure 150 may represent athree-dimensional structure containing a plurality of metal regionscorresponding to the metal regions 111 and to a certain degree to thevias 115, and dielectric material comprised in the various dielectriclayers 116 and any dielectric capping layers such as the layer 113.Consequently, an x-ray beam 160, impinging on the device 100, mayundergo interaction with the material contained in the structure 150,wherein the type of interaction significantly depends on thecharacteristics of the various materials, as well as on thecharacteristics of the incident x-ray beam 160. For example, formoderately high beam energies of several keV as are typically requiredfor performing a crystallographic analysis of materials, a penetrationdepth of the beam 160 may be greater than or comparable to the thicknessof the metallization structure 150, thereby providing a plurality ofreflected or scattered and transmitted beams 161, 162 which may haveinteracted with the metallization structure 150 at varying thicknesses.For example, the uppermost metallization layer M6 or 110N may be “seen”by the incoming x-ray beam 160 as a material surface comprising a metalhaving formed therein a plurality of metal grains, such as the grains117, having a specific size and orientation. Consequently, a fraction ofthe incident beam 160 may interact with the crystallographic structurein the grains 117, thereby producing a reflected or scattered beam for aspecified angle of incidence for a specified beam energy, i.e.,wavelength, when a specified entirety of crystalline planes meets theBragg condition. Similarly, due to restricted thickness of the uppermostmetallization layer 110N, most of the incident beam 160 may furtherproceed into the structure 150, thereby encountering further metalgrains, which may also interact with the incident beam in order toproduce reflected and scattered beam components. It should beappreciated that other material components, such as the dielectricmaterials, may interact with the incoming beam, thereby also producingsecondary radiation which may be included in the beams 161 and 162.Consequently, the entirety of beams 161, 162, which may be detected byappropriate detection means, such as semiconductor detectors and thelike, may include information regarding the entirety of the stack 150,which may also include information of the response of the individuallayers 110A . . . 110N to the incident beam 160 or the respectiveportions thereof after interaction within the structure 150. In order toobtain information on the texture-specific characteristics of themetallization structure 150 in a more spatially localized manner,“three-dimensional” information reflecting the response of a certainvolume of the structure 150 and contained in the beams 161, 162 may be“reduced” so as to obtain substantially “two-dimensional” information,which may represent information on a substantially horizontal “slice” ofthe structure 150. For instance, the plurality of beams 161 may bedetected and may be analyzed by any appropriate analysis technique forobtaining structural information with respect to the size and/ororientation of the grains 117, wherein measurement data and/or amanipulated version thereof may be related to appropriate “reference”data in order to estimate the magnitude of the effect, which may beprovided, for instance, by the uppermost metallization layer 110Ncompared to the rest of the layers 110A, 110B, 110C, 110N. Consequently,as indicated in FIG. 1 c, the measurement data represented by the beams161 may be manipulated so as to “extract” information related to aportion 164 that substantially corresponds to the uppermostmetallization layer 110N on the basis of appropriate reference datarepresenting the combined information corresponding to the scattered orreflected beams 163, although these beams are actually not separated.

Consequently, the three-dimensional information included in theplurality of scattered beams 161 may be reduced to the “two-dimensional”information corresponding to the beam component 164. It should beappreciated that the scattered beam 161 is actually a single beam or aportion thereof which may be detected by a corresponding detectorelement and the above process of data reduction does not provide real“separated” beams, as is illustratively depicted in FIG. 1 c. Rather,the data reduction should be understood as a data manipulation, in whicha wanted signal is extracted from a “noisy” underground, i.e., theinformation produced by the lower-lying layers, in order to obtain theinformation contained in the portion of the detected beam thatsubstantially contains the information originating from the interactionwith the layer 110N, wherein the corresponding “beam” 164 illustrated inthe figures may, however, not be physically separated from the remainingbeam components 163 stemming from an interaction with the remainingmetallization layers. For example, in some illustrative embodiments, theincident x-ray beam 160 may be provided as a substantiallymono-energetic beam having an energy of several keV, wherein an angle ofincidence may be varied and the resulting scattered or transmitted beams161 may be detected and recorded. Based on the resulting intensityvariation with respect to the angle of incidence, in combination withthe provision of appropriate reference data, which may representunwanted signal portions stemming from the metallization layers 110A,110B, 110C, 110N, information about the orientation and/or size of thegrains of the metallization layer 110N may be extracted. In otherillustrative embodiments, the beam 160 may comprise a plurality ofdifferent wavelength components and an angle of detection for thescattered beams 161 may be varied in order to obtain a correspondingintensity variation for extracting information on the crystallinity ofmetallization layer 110N.

Appropriate reference data may, in some embodiments, be established onthe basis of reference measurements, possibly in combination withrespective simulation calculations, as respective electromagneticinteractions in a wide variety of materials is well understood andcorresponding calculations may be performed with high accuracy,depending on the available computational resources. For instance,simulation calculations may be performed in advance for a variety ofdevice configurations for each of the metallization layers 110A, 110B,110C, 110N on the basis of appropriate material models, especially forthe metal grains 117, in order to obtain a plurality of quantitativeintensity distributions of the simulated “scattered beams.” For example,for a substantially ideal metallization structure 150, it may be assumedthat, in each metallization layer, a high uniformity in grain size andgrain orientation may be obtained during manufacturing and may still bemaintained during the formation of any subsequent metallization layers,which may be assumed to also have respective grain sizes andorientations. With a correspondingly assumed configuration, theresulting intensity distribution with a varying angle of incidence for agiven beam energy may be calculated. Similarly, for one or more of thelayers 110A, 110B, 110C, 110N, a different configuration may be assumed,for instance by altering the (virtual) distribution of grainorientations in the respective metal lines and the like, and acorresponding simulation result may be recorded as a further set ofreference data. Based on a plurality of respective different sets ofreference data, an appropriate process of data reduction for actualmeasurement data obtained from the beam 161 may be performed to estimatethe texture of one or more of the layers 110A, 110B, 110C, 110N, whereinthe reference data may be stored in a library in order to enhance dataprocession speed when comparing the measurement data with the referencedata. Additionally or alternatively, the process of data reduction maybe based on reference measurements, as will be described with referenceto FIGS. 1 d and 1 f for further illustrative embodiments of the presentinvention.

FIG. 1 d schematically illustrates a cross-sectional view of themicrostructure device 100 in an early manufacturing stage, wherein itshould be appreciated that the structure 100 may not actually representthe identical structure as shown, for instance, in FIG. 1 c after theformation of six metallization layers, but may represent an equivalentstructure having formed thereon the first metallization layer 110A. Inthis manufacturing stage, the x-ray beam 160 may be provided as asubstantially mono-energetic beam, wherein the angle of incidence,indicated as α, may be varied within an appropriate range of values, forinstance for enabling the identification of one or more crystallographicorientations of interest within the metal regions in the layer 110A. Theresulting scattered or reflected beam 161 may be detected by anyappropriate detector in order to obtain the corresponding intensity ofthe beam 161 with a variation of the angle of incidence α. For example,at the right side of FIG. 1 d, a corresponding diagram mayillustratively represent an intensity distribution for the beam 161 overa certain range of angles of incidence α. It should be appreciated thatthe diagram of FIG. 1 d is only of illustrative nature wherein, forinstance, actual measurement data may be appropriately manipulated onthe basis of well-established techniques, such as data smoothing, datafitting and the like. Moreover, respective measurement data, indicatedas M1, as represented by the diagram of FIG. 1 d may, in some cases, beobtained on the basis of a moderately high number of samples processedon the basis of substantially identical process conditions in order toenhance the statistical relevance of the respective measurement data. Instill other illustrative embodiments, the measurement data obtainedaccording to FIG. 1 d may also be correlated to measurement dataobtained by other measurement techniques, such as electron microscopy,in order to obtain a quantitative measure or additional information thatenables the categorization of the x-ray measurement data, when combiningmeasurement data of different samples.

FIG. 1 e schematically illustrates the microstructure device 100 in afurther advanced manufacturing stage, in which a further metallizationlayer 110B is formed on the first metallization layer 110A, wherein itshould also be appreciated that the device 100 may not necessarilyrepresent the same device 100 as shown in FIG. 1 d, but may represent anequivalent device in which the first metallization layer 110A issubstantially equivalent to the layer 110A of FIG. 1 d. Similarly asdescribed above, a portion of the device 100 may be irradiated with thex-ray beam 160 of specified characteristics and the resulting scatteredor reflected beam 161 may be detected. The corresponding measurementdata may be represented by a corresponding diagram as shown at the rightside of FIG. 1 e, wherein the resulting intensity distribution nowrepresents the combined response of the layers 110A and 110B to theincident beam 160. Thus, the corresponding measurement result mayinclude the desired information with respect to the metallization layer110B, which however is “obscured” by the information produced by thefirst metallization layer 110A (and of course by the substrate 101).Consequently, in some illustrative embodiments, the previous measurementdata or any manipulated version thereof may be used as reference data,which may be related or, in illustrative embodiments, “subtracted” inany appropriate form in order to produce respective measurement datasubstantially corresponding to the response of the metallization layer110B.

FIG. 1 f schematically illustrates a corresponding simplified datamanipulation sequence for obtaining an appropriate measurement data setfor estimating the texture-specific characteristics of the metallizationlayer 110B. For instance, the reference data or measurement data M1obtained during the first measurement according to FIG. 1 d may be“subtracted” from the second measurement data M1+M2 obtained during themeasurement according to FIG. 1 e in order to obtain differential dataM2 as indicated by the right side of the “equation” illustrated in FIG.1 f. It should be appreciated that the “subtraction” operation asindicated in FIG. 1 f may include any appropriate data manipulationprocess for producing the differential data M2. For instance, aspreviously indicated, the raw data may be subjected to data smoothing,fitting, peak detection and the like prior to performing the datareduction according to FIG. 1 f. Moreover, again referring to FIGS. 1 dand 1 e, it may be appreciated that the situation for the firstmetallization layer 110A in FIG. 1 e is different compared to themetallization layer 110A of FIG. 1 d, even though the incident beam 160may be identical in both cases. That is, while according to FIG. 1 d thecompletely “undisturbed” beam 160 penetrates the metallization layer110A, according to FIG. 1 e a modified version, indicated as 160S, ofthe beam 160 may impinge on the first metallization layer 110A, sincethe beam 160 has already undergone significant interaction with thesecond metallization layer 110B. Consequently, at least the intensity ofthe beams 160S and 160 incident on the first metallization layers 110Aof FIGS. 1 d and 1 e is different and also the divergence of the beam160S may be increased compared to that of the beam 160. Consequently, insome illustrative embodiments, the corresponding effect caused by thedifference in the incoming beams 160 and 160S may be taken intoconsideration prior to the data reduction corresponding to FIG. 1 f inthat the respective reference data M1 may be “corrected” by anappropriate correction factor or correction function. For instance, areduced height of the intensity distribution of the reference data M1,possibly in combination with a broader distribution around correspondingpeaks, may be used for the corresponding data reduction according toFIG. 1 f in order to take into consideration the reduced intensity andthe increased divergence of the beam 160S.

Moreover, as previously explained, the measurement data M1 and M1+M2 orM1−M2 may be compared with respective simulation calculations in orderto more clearly identify respective crystallographic characteristicsand/or to enhance the authenticity of the respective simulations.Furthermore, the second measurement data M1+M2 obtained according to,for instance, a measurement process as shown inure FIG. 1 e may also beused as respective reference data for measuring a subsequentmetallization layer, that is, the third metallization layer 110C,according to the same principles as outlined with reference to FIGS. 1d-1 f . Thus, the metallization structure 150 as shown in FIG. 1 c maybe measured with respect to the texture characteristics of the uppermostlayer 110N on the basis of respective reference data obtained for thelayers 110A, 110B, 110C, 110N, similarly as is described above.Depending on the amount of available reference data, respective “layerresolved” texture-specific information may also be extracted forintermediate metallization layers by correspondingly correcting for theinfluence of overlaying and underlying layers. It should be appreciatedthat, due to the low impact of the x-ray beam 160 on the characteristicsof the metallization structure 150 in combination with the highpenetration depth and the moderately low effort for sample preparation,corresponding measurement data may be readily gathered on fully embeddedand operational structures, thereby rendering the measurement techniquebased on x-ray analysis with a respective data reduction highlyadvantageous for identifying failure mechanisms and for identifyingrelevant process parameters of a respective manufacturing process.

With reference to FIG. 2, further illustrative embodiments of thepresent invention will now be described in more detail, in which themonitoring and investigation of texture characteristics during specifiedstress conditions may be performed on the basis of the above-describedmeasurement techniques.

In FIG. 2, a system 200 comprises an x-ray source 201 and an x-raydetector 202 that is configured to detect scattered or reflectedradiation generated by the incoming x-ray beam, as is previouslydescribed with reference to the x-ray beam 160 and the correspondingscattered or reflected beams 161 and 162. Moreover, the detector 202 isconfigured to provide respective measurement data, such as intensityvalues, wherein the radiation source 201 and the detector 202 may beconfigured to operate with varying angles of incidence. Furthermore, thedetector 202 is connected to a signal processing unit 203 configured toobtain respective measurement data and manipulate and/or store therespective data. The system 200 further comprises a sample holder 205configured to receive and hold in position an appropriate sample, suchas the microstructure device 100 as described with reference to FIGS. 1a-1 e. The sample holder 205 may represent any appropriate processchamber for applying specified stress conditions, which may for instancecomprise respective environmental conditions, such as temperature,humidity, pressure and the like. For example, the system 200 maycomprise an adjustable current source 204 that may be connected to themicrostructure device by appropriate contact pads (not shown). Moreover,the system 200 may comprise a heater 206 configured to adjustablyprovide heat to the sample holder 205 in order to adjust the temperatureof the respective sample. Furthermore, the system 200 may comprise astorage unit 210 for receiving corresponding data from the signalprocessing unit 203, for instance in the form of intensity distributionsas are illustratively shown in FIGS. 1 e-1 f, or in any other form thatindicates a characteristic of the grain size and/or orientation, whereina part of the respective data may be used as reference data, as ispreviously described. Moreover, respective data of simulationcalculations may also be stored in the unit 210 or may be generated ondemand within the unit 210 by means of appropriate computer means.Furthermore, the system 200 may comprise a data reduction unit 220configured to operate on respective data sets stored in the storage unit210 so as to obtain relevant reduced or differential data, from whichrespective information on texture-specific characteristics may beextracted. For instance, the unit 220 may be configured to automaticallyestimate the distribution of grain orientations on the basis ofrespective differential data, such as a data M1−M2 as shown in FIG. 1 f,by, for instance, identifying a width and/or a position of a respectivepeak or maximum of the intensity distribution, and/or by comparing therespective differential data with appropriate reference data for avariety of configurations for respective metal grains.

During the operation of the system 200, an appropriate sample, such asthe device 100, may be mounted on the sample holder 205 and specifiedstress conditions may be applied. Since the investigation ofelectromigration is of great interest for the development ofinterconnect structures of highly complex integrated circuits,preferably the stress condition includes the application of a specifiedcurrent by means of the adjustable current source 204 to create aspecific initial current density in one or more layers of interest, suchas the upper-most metallization layer, as is for instance shown in FIG.1 c. Furthermore, the sample holder 205 may be heated to a specifiedtemperature, or a specific temperature distribution may be generated inorder to induce a specific temperature gradient within the respectivemeasurement sample.

During the application of the specified stress conditions, the x-raybeam may be directed to the sample, either continuously orintermittently at predefined time intervals, and the correspondingscattered or reflected radiation is received by the detector 202. Forinstance, the sample may be provided in the form of a lamella and thetransmitted or scattered or reflected x-ray beam may be detected andprocessed to provide the respective differential or reduced data thatenables the estimation of the corresponding texture-specificcharacteristics. Depending on the computational resources and amount ofdata manipulation and process simulation, respective information on thetexture characteristics may be obtained in a substantially real-timefashion and may be made visible in a substantially time-related fashionwith respect to the process conditions, while, in still otherembodiments, the corresponding measurement data may be stored and may beanalyzed at any later stage. Consequently, a correlation betweenstress-induced degradation mechanisms and texture characteristics may beefficiently established to detect relevant degradation mechanisms. Sincesample preparation is significantly less complex compared to thepreparation of samples for electron microscopy, respective data may bereadily obtained within a reasonable time period, thereby also enablingan effective process control for the fabrication of complexmetallization structures.

FIG. 3 schematically represents a process sequence 300 for forming ametallization structure, as is for instance described with reference toFIG. 1 a. Box 310 represents processes related to the formation of aconductive barrier layer and possibly a seed layer, wherein theseprocesses may include chemical and physical vapor deposition, atomiclayer deposition, electroless plating processes and the like. Box 320represents any inspection processes performed after having formed thebarrier layer. Box 330 represents the deposition process for the bulkmetal, such as copper, on the basis of electroplating or electrolessplating. Moreover, Box 330 is to represent any post-plating processessuch as CMP, electro-polishing and the like for removing any excessmaterial. Moreover, anneal cycles performed prior to and/or after theCMP process may also be represented by Box 330, wherein highly advancedanneal techniques or other treatments for obtaining enlarged metalgrains may be included, the efficiency of which may thus be effectivelymonitored and/or controlled on the basis of the x-ray measurementtechnique described above. Box 340 indicates the deposition of any typeof capping layer, such as dielectric or conductive capping layers,followed by Box 350 representing inspection and other measurementprocedures, such as measurement processes described with reference toFIGS. 1 c-1 f and 2, for evaluating the texture characteristics of thecorresponding metal lines. Thereafter the sequence 300 may be repeatedwith appropriately adapted parameter values to form furthermetallization layers.

In the process steps 310, 320, 330, 340, 350, materials and processparameters may change in accordance with device and process requirementsfor the microstructure of interest since, for example, the grain sizeand orientation, which may be influenced by the process strategies andthe materials used, may be essential for the proper operation of themetallization structure and may even become more important as featuresizes are steadily decreased. As previously explained, a complex mutualinteraction of the materials and process parameters may significantlyinfluence the finally obtained crystalline structure. Therefore,according to one illustrative embodiment, an in situ measurement whichmay also include a degradation test, represented by Box 360, may beperformed similarly as is described with reference to FIGS. 1 c-1 f and2, thereby enabling a sensitive monitoring of the involved materials andprocess parameters. For instance, a change of the geometry, i.e., thedimensions of the metal lines, may lead to subtle changes of the grainorientation and/or size, although substantially the same processparameters and materials may have been used in the manufacturingsequence 310, 320, 330, 340, 350 as in previously fabricatedmetallization structures exhibiting satisfactory results.

Based on the in situ test 360, a corresponding correlation between oneor more materials or process parameters may be established with respectto their influence on the finally obtained crystallinity of therespective metal regions. Consequently, process flow failures may bereadily identified on the basis of the respective measurement results.Moreover, the in situ test 360 enables efficient monitoring of processvariations within the sequence 310, 320, 330, 340, 350 which may nothave been identified within the individual processes. For instance, itmay be assumed that, according to results provided by the inspectionprocesses 320 and 350, or other additional metrology processes, theindividual processes 310, 330 and 340 may lie within the respectivelydefined process margins, while nevertheless the finally obtainedmetallization structure may have a non-desired texture identified by thetest 360. In other embodiments, a correlation may be established asindicated by 370 that relates at least one process parameter and/ormaterial to the measurement results obtained by the test 360 so that a“long term” process control may be achieved. For instance, frompreviously performed reference measurements, an influence of, forexample, process materials and parameters of the barrier/seed depositionprocess 310 may have been determined for a plurality of materials andprocess parameter values. Upon detection of a deviation of periodicallyperformed tests 360, a corresponding re-adjustment of process parametersand/or materials may then be performed. Thereafter, one or moresubsequent substrates may be processed on the basis of the re-adjustedparameters and/or materials. The same holds true for the further processsteps 320, 350. For instance, measurement results of the inspectionsteps 320 and 350 may be effectively correlated with the results of thein situ test 360, thereby providing the capability for detectingrelevant process fluctuations at an early stage in the sequence 300. Forexample, the measurement results with respect to the texture, that is,grain size and/or grain orientation, may be related to degradationmechanisms identified by the test 360, wherein, by means of thecorrelation 370 and corresponding routinely performed measurements, aprocess may be identified which may have otherwise been estimated asadequate. In this way, the “sensitivity” of one or more inspectionprocesses involved in the sequence 300 may be enhanced with respect tothe finally obtained reliability of metallization structures.

As a result, the present invention provides an enhanced technique forthe inspection of texture and crystallinity of metal lines in a stackedmetallization structure on the basis of x-ray techniques combined withdata reduction in order to obtain measurement results for individualmetallization layers in the metallization stack. For this purpose,appropriate “reference data” may be obtained to “reduce” thesubstantially three-dimensional data of the entire stack in anappropriate fashion to allow the extraction of information of onespecific metallization level. Consequently, the advantages of x-rayanalysis with respect to sample integrity as well as sample preparationcompared to charged particle measurement techniques may be used whilestill providing the possibility of “resolving” the measurement resultsto individual metallization layers. Consequently, the influence ofprocess parameters and materials on the crystalline structure of metallines may be investigated more efficiently and furthermore the relationbetween electromigration or other stress-induced transport phenomena andthe crystallinity of respective metal lines may be examined and mayallow an efficient identification of degradation mechanisms and/orprocess control.

The particular embodiments disclosed above are illustrative only, as theinvention may be modified and practiced in different but equivalentmanners apparent to those skilled in the art having the benefit of theteachings herein. For example, the process steps set forth above may beperformed in a different order. Furthermore, no limitations are intendedto the details of construction or design herein shown, other than asdescribed in the claims below. It is therefore evident that theparticular embodiments disclosed above may be altered or modified andall such variations are considered within the scope and spirit of theinvention. Accordingly, the protection sought herein is as set forth inthe claims below.

1. A method, comprising: irradiating a portion of a first stackedmetallization structure of a microstructure device with an x-ray beam ofspecified characteristics, said first stacked metallization structurecomprising a plurality of layers, each layer comprising a metal region;obtaining first measurement data of a plurality of said metal regions ofsaid portion on the basis of said x-ray beam wherein said plurality ofmetal regions is located in two or more of said plurality of layers;manipulating said first measurement data to obtain manipulated datarelating to a texture of one or more of said metal regions; andextracting information for at least one of said plurality of stackedlayers about said texture on the basis of said manipulated data.
 2. Themethod of claim 1, wherein manipulating said first measurement datacomprises: irradiating a second stacked metallization structure of amicrostructure with an x-ray beam having said specified characteristicsto obtain second measurement data, said second metallization structureformed according to the same design rules as said first metallizationstructure and having a reduced number of layers compared to said firstmetallization structure; and relating said first measurement data tosaid second measurement data to obtain said manipulated data.
 3. Themethod of claim 2, wherein said first stacked metallization structurecomprises n layers and said second stacked metallization layer comprisesn-1 layers and wherein a last layer of said second stacked metallizationstructure corresponds to a penultimate layer of the first stackedmetallization structure.
 4. The method of claim 2, wherein obtainingsaid manipulated data comprises subtracting a first data correlated tosaid first measurement data from a second data correlated to said secondmeasurement data to obtain differential data and using the same forobtaining said manipulated data.
 5. The method of claim 4, whereinobtaining said manipulated data further comprises applying at least onecorrection algorithm to said differential data and using said correcteddifferential data as said manipulated data.
 6. The method of claim 1,wherein extracting said information about a texture of at least one ofsaid plurality of layers comprises evaluating at least one of a grainsize and an orientation of grains formed in each of said metal regions.7. The method of claim 1, wherein irradiating said first stackedmetallization structure to said x-ray beam of specified characteristicscomprises forming a substantially mono-energetic x-ray beam and varyingan angle of incident of said x-ray beam.
 8. The method of claim 7,further comprising detecting an intensity of an x-ray beam reflectedfrom said portion for a plurality of different angles of incidence. 9.The method of claim 1, wherein irradiating said first stackedmetallization structure to said x-ray beam of specified characteristicscomprises forming an x-ray beam having a plurality of differentwavelengths and directing said x-ray beam onto said portion under aspecified angle of incidence.
 10. The method of claim 9, furthercomprising detecting an intensity of an x-ray beam reflected from saidportion for a plurality of different detection angles.
 11. The method ofclaim 10, further comprising establishing specified stress conditionsfor said first stacked metallization structure and obtaining, as saidfirst measurement data, a plurality of data sets corresponding to saidspecified stress conditions.
 12. The method of claim 11, wherein saidspecified stress conditions comprise a condition to causeelectromigration effects to occur in said metallization structure. 13.The method of claim 11, further comprising visualizing said extractedinformation while said specified stress conditions are applied to obtaina time progression of a variation of said texture.
 14. A method,comprising: forming a stacked metallization structure of amicrostructure device according to a specified manufacturing sequence,said stacked metallization structure comprising a plurality ofmetallization layers; obtaining information about a texture of metalregions located in two or more of said plurality of metallization layerson the basis of x-ray analysis; correlating at least one processparameter used in said specified manufacturing sequence with saidtexture information; and controlling said at least one process parameteron the basis of said correlation.
 15. The method of claim 14, whereinsaid information relates to at least one of a size and an orientation ofgrains formed in said metal regions.
 16. The method of claim 15, whereinsaid texture information is obtained for each of said plurality ofmetallization layers.
 17. The method of claim 14, wherein saidmetallization structure comprises copper and a low-k dielectricmaterial.
 18. The method of claim 14, wherein obtaining said informationcomprises obtaining first measurement data from a first metallizationlayer, obtaining second measurement data from a second metallizationlayer, obtaining differential data from said first and secondmeasurement data and extracting said information on the basis of saiddifferential data.
 19. The method of claim 14, further comprisingdetermining a relationship between said information and at least onestress-induced degradation process and controlling said specifiedmanufacturing sequence on the basis of said relationship.
 20. A method,comprising: providing a metallization structure of a microstructuredevice, said metallization structure comprising a plurality of stackedmetallization layers, each metallization layer comprising a metal regionwith metal grains; subjecting said metallization structure to predefinedstress conditions; and estimating a distribution of grain orientationsin at least one of said plurality of stacked metallization layers byx-ray analysis that covers two or more of said plurality of stackedmetallization layers under said predefined stress conditions.
 21. Themethod of claim 20, wherein estimating a distribution of grainorientations comprises: obtaining first x-ray measurement data from saidmetallization structure; obtaining second x-ray measurement data from areference metallization structure including a lower number of stackedmetallization layers compared to said metallization structure; andobtaining differential data on the basis of said first measurement dataand said second measurement data to estimate said distribution based onsaid differential data.